Low-latitude upper atmosphere is replete with the effects of various intriguing and inter-coupled phenomena that are generated over equatorial latitudes.  As a consequence of these phenomena, the upper atmosphere from the latitudes close to the magnetic equator to those that are farther away respond in varying degrees wherein neutral- and plasma densities, and gravity wave features, vary as a function of latitude.  Further, the neutral thermospheric gravity wave propagation characteristics also change with latitude.  From the analysis of thermospheric and ionospheric datasets obtained using optical, radio-wave, and magnetic techniques from strategic locations in the northern hemisphere over Indian longitudes, we have obtained several new results, corresponding to both, in the daytime and nighttime upper atmosphere.  These include influence of meridional neutral winds on the variation of nocturnal redline airglow emissions, quantification on the latitudinal extents of the response of the daytime equatorial ionization anomaly as seen in the daytime oxygen airglow emission at multiple wavelengths, and seasonal dependence of the existence of vertical propagation of gravity waves.  The results obtained from the low latitudes enhance our understanding of the ionosphere thermosphere coupling over both magnetic quiet and disturbed conditions. In this talk some of these new and insightful results will be discussed.

The purpose of this study is to comprehensively understand the evolution of global 3D current system from polar to equatorial ionosphere during substorms.There are two types of current in the polar ionosphere: the R1-current linked to the magnetospheric convection system, and the R2-current linked to the pressure gradient in the inner magnetosphere [Iijima and Potemra, 1976, 1978]. In addition to these currents, when a substorm onset is occurred by a strong plasma injection, a current wedge (CW) is generated by the plasma vorticities at the edge of the plasma flow. It has the same current polarities as the R1-current system. At the lower latitude of the CW, an R2-type current system develops by increasing the plasma pressure. It weakens the effect of ionospheric current associated with the CW system reaching low latitudes and equatorial regions. This is called a shielding effect. Furthermore, it sometimes overcomes the effect of CW, and grows of current systems in the opposite direction. This is called an over-shielding effect. (Kikuchi et al.,1996 ; Nishida.,1968). The ground magnetic field disturbances during substorms are generated by not only the ionospheric currents, but also the field-aligned currents (FACs) accompanied by the growth of the CW. These effects are particularly large in the mid- and low-latitude. It is difficult to determine from the magnetic field data alone whether the magnetic field variation is due to the ionospheric current system or to the remote effect of the CW system. A direct comparison of ionospheric electric and magnetic field data is essential for a better understanding of the causes of magnetic disturbances.  In this presentation, we report the results of a study of mid-latitude ionospheric variability during substorm using electric field data from the HF Doppler radar and magnetic field data from SuperMag and MAGDAS.

The presence of Equatorial Electrojet (EEJ) enhances the conductivity of equatorial ionosphere and enable the penetration of Interplanetary electric field through high latitudes known as prompt penetration effects (PP). Using five years (2011-2015) of geomagnetic data at a site VEN local time dependence of PP amplitude and its relation to IMF-Bz turning for both quite (Kp<3) and disturbed (Kp≥3) time is being studied; the number and amplitude of PP events are larger during local noon time for both quiet and disturbed time is attributed to the high ionization. The amplitudes of PP during quiet days are observed to be similar for both IMF-Bz north and south turnings, whereas for disturbed days PP amplitudes observed to be higher for IMF-Bz north turning, this might be due to the overshielding effects. The PP events associated with IMF-Bz northward turning during magnetically quiet time creates depression/westward current in the EEJ sometimes appears as equatorial counter Electrojet (CEJ). Few PP events are observed while equatorial electric field at VEN is already in westward direction (i.e PP within CEJ). The analysis of one year of concurrent geomagnetic data from MNC, VEN and CBY shows that PP amplitude varies significantly (10nT>) between sites which are 15° & 20° longitudes apart. The analysis also shows a trend of increase in PP amplitudes toward west of India (i.e toward MNC).

The bottomside of the ionosphere rapidly decays after sunset and develops a sharp vertical density gradient on the lower layer that triggers plasma density perturbation in the ionosphere. Equatorial plasma bubbles (EPBs) and plasma blobs (enhancements) are evidence of nighttime ionospheric plasma instabilities in the low-latitude ionosphere. This study presents plasma density (EPB and blob) structures identified using simultaneous in-situ measurement by the SWARM satellite constellation and concurrent total electron content (TEC) detected from ground-based Global Positioning System (GPS) receivers in the American low-latitude region. The ground-based GPS receivers diagnose bubbles and blobs characteristics in terms of TEC values. Basically, the space-based observations of ionospheric plasma density from the Swarm constellation were supported by the ground-based observations. The comparative ground- and satellite-based observations indicate that the ground-based data show the variability of the background ionosphere prior, during, and after the development time of the EPBs as seen by the SWARM. For this limited analysis, the plasma blob events are seen near the low and mid-latitude boundary region. Further, the zonal motion of the density structures detected by SWARM and the drift of TEC structures seen with GPS receivers are in good agreement. Based on an observational standpoint, the possible mechanism of the generation, evolution, and relationship between EPBs and plasma blobs in the F-region ionosphere will be described in detail.

The quiet time characteristics of equatorial electrojet (EEJ), counter electrojet (CEJ), and solar quiet (Sq) day geomagnetic field over two decades (1980–2002) are established using Principal component analysis (PCA) from equatorial (Ettaiyapuram) and off‐equatorial (Hyderabad) Magnetic Observatories, India, over sunspot cycles 21–23. The patterns of normal field show that the diurnal amplitudes were strong during equinox compared to other seasons. Varying contributions of abnormal field in different Lloyd's seasons were evident in different phases of sunspot cycle. The diurnal amplitudes have reduced from the 21st to the 23rd sunspot maxima following the trend of weakening of sunspot cycle. Analysis of seasonal means shows evening CEJs were more pronounced when compared to morning and afternoon in different phases of sunspot cycle. The abnormal field variations have a strong correlation with the occurrence of afternoon CEJs during solar minima; a correlation of seasonal occurrences of CEJs with phases of sunspot cycles is revealed.

We performed a superposed epoch analysis of solar wind, interplanetary magnetic field, geomagnetic index, and the rate of total electron content (TEC) index (ROTI) derived from global navigation satellite system-TEC data during 652 geomagnetic storm events (minimum SYM-H < -40 nT) for 19 years (2000–2018), to clarify the occurrence features and causes of storm-time plasma bubbles in the equatorial to mid-latitude ionosphere. In this analysis, we defined the time of the SYM-H minimum as the zero epoch. As a result, the ROTI enhancement started at the duskside magnetic equator and expanded to higher latitudes during the main phase. Approximately 1 h after the onset of the recovery phase, the ROTI values at the magnetic equator in the dusk-to-midnight sectors decreased while those in the dawn sector increased. This situation persisted for at least 12 h. On the other hand, the ratio of the ROTI during the main phase to that during the quiet period in the dusk sector is the largest in May–July. The ratio of the ROTI in the dusk sector during the main and recovery phases decreased with increasing solar activity. Considering the requirement of the Rayleigh-Taylor instability, the difference in the magnetic local time of the ROTI signature, between the main and recovery phases, can be explained by a local time distribution of storm-time electric fields associated with a prompt penetration electric field and disturbance dynamo. This implies that the occurrence feature of the plasma bubble is different from that during quiet times when the input of solar wind energy to the magnetosphere and ionosphere increases significantly.

The quasi-6-day wave (Q6DW), one of the atmospheric waves, is excited in the lower atmosphere and propagates into thermosphere. Using CHAMP, Swarm and Aura satellites, Yamazaki et al. showed that the quasi-6-day oscillation in the EEJ occurs when the Q6DW in the mesosphere is enhanced. This suggests that the quasi-6-day oscillation in the EEJ is caused by the Q6DW propagating from below. We analyzed that the magnetic field data on 210°geomagnetic longitude chain of global geomagnetic observation network (MAGDAS) and an atmosphere-ionosphere coupled model (GAIA). Our results indicate that the quasi-6-day oscillation in the Sq-EEJ current system more strongly developed in the mid-latitude Sq current system than in the EEJ, and more strongly developed in the day side. Also, the quasi-6-day oscillation of the GAIA and MAGDAS have similar seasonal variation and latitudinal structures. The quasi-6-day oscillation is strongly developed in equinoxes, which is consistent with the seasonal dependence of the excitation source, the Q6DW.However, how the Q6DW effects on the electrical conductivity and the electric field is not well known. The excitation mechanism of the quasi-6-day oscillation in the Sq-EEJ current system is examined using GAIA. That leads to understand coupling processes in the atmosphere-ionosphere system.

Abstract: The Energetic Particle Instrument (EPI), proposed by the Peking university (PKU) team, consists of three dual double-ended foil/magnet semiconductor telescopes. The magnet telescope side utilizes three layers of semiconductors, respectively, with a 50-micron thickness, 500-micron thickness and 500-micron thickness to measure protons at energies from 30 keV to 12 MeV. The front of the 50-micron thick detector is surrounded by a magnet to sweep away electrons below 400 keV but let protons pass. This paper describes the design and GEANT4 simulations of the proton detection side of the PKU EPI.

We present a statistical study of the spectral shapes of 8 solar energetic electron events detected in the ~1 to 300 keV range near the earth, from 1995 to 2019, by using WIND 3D plasma instrument. After taking times of pre-event into account, among 8 cases, 6 cases exhibit a single-power-law spectrum with a “curved platform” and the other two exhibit a double-power-law spectrum of β₁ ~2.2±0.2 and β₂ ~5.5±0.4, also with a “curved platform”. Consistently, the “curved platforms” are regular in width and shape, emerging at about 40 keV, around the traditional break energy range of most events whose spectrum exhibits double-power-law. Furthermore, after comparing with other solar activities, these cases all have a close association with type III bursts, SXR flares, hard X-ray emission and appear to be unassociated with CME. Especially, related hard X-ray photon spectrums also exhibit similar “curved platform”, suggesting this phenomenon may be directly caused by source region.

Energetic Neutral Atoms (ENA) at the interstellar boundary that originated through the charge exchange processes between the solar wind energetic particles and interstellar neutral wind have shown many interesting features uncovered by Cassini and IBEX observations, and at the same time bring more unsolved problems. ENAs at higher energy still lacks enough observations. In this study we demonstrate the physical design of a grid-based energetic ENA imager that can provide high temporal, spatial and energy resolution ENA imaging of interstellar boundary region. The ENA imager takes advantage of spatial Fourier modulation to the ENA fluxes to construct the ENA images, which is inspired by RHESSI. The physical design including imaging process, the charged particle reflector, and the ENA species discrimination etc. are described, along with the engineering progresses. The ENA imager can be unitized in future interstellar exploration missions.

The Energetic Particle Instrument (EPI), proposed by Peking University for the future interstellar mission, is designed to provide the three-dimensional distribution of suprathermal electrons and ions with good time, energy and angular resolutions in the interplanetary space, respectively, at energies from 20 keV to 1 MeV and from 20 keV to 11 MeV.  The EPI consists of dual double-ended foil/magnet semi-conductor telescopes, which cleanly separate electrons in the energy range from 20 to 400 keV and ions from 20 keV to 6 MeV. The magnet of semi-conductor telescopes consists of two pairs of Nd₂Fe₁₄B permanent magnets with soft iron frames. Due to the high saturation polarization and high magnetic anisotropy of the Nd₂Fe₁₄B strongly magnetic matrix phase, this system can make the magnetic field strong enough to make the electrons deflected. A frame made of aluminum alloy combines two pairs of magnets and cause the magnetic field to decay rapidly in the far field. In this way, the two air gaps in the system can simultaneously provide a deflecting magnetic field for a pair of anti-parallel sensor systems.

The PKU energetic particle instrument (EPI) is designed to make measurements of the three-dimensional distribution of suprathermal electrons and ions with good time, energy and angular resolutions in the interplanetary space, respectively, at energies from 20 keV to 1 MeV and from 25 keV to 12 MeV.  The EPI consists of three dual-double-ended foil/magnet semi-conductor telescopes to cover a solid angle of close to 4π steradians. Each double-ended telescope has four silicon semiconductor layers: in one direction, the front semiconductor layer is covered with a thin foil to stop protons at energies below ~400 keV but leave the electron spectrum essentially unchanged; in the opposite direction, the front semiconductor layer looks through cylindrical magnets that sweep away electrons at energies below ~400 keV but leave ions unaffected. The EPI also employs the well-established dE/dx vs. total energy approach to determine the nuclear charge and mass of some ion species.

We report the science objectives, design of instruments, and recent updates of the development of the far-ultra violet (FUV) imager for the future polar orbiting satellite FACTORS. This design is also applicable to the FUV imager on a geostationary orbiting satellite conducted by NICT, Japan. FACTORS stands for Frontiers of Formation, Acceleration, Coupling, and Transport Mechanisms Observed by the Outer Space Research System, which is going to be proposed as a next-generation multi-satellite formation flight mission. Major scientific targets are: 1) energy transport in the magnetosphere-ionosphere (MI) coupling system and their relationship to small-scale auroral phenomena, 2) particle transport in the MI system by ion outflow, and 3) neutral-ion coupling in the auroral thermosphere. We give the status of design and development of visible and FUV imagers for this mission. Both visible and FUV images are required to have high-spatial and high-time resolution capability to observe the dynamical morphology of small-scale aurora. Therefore, we set the instrumental requirement for the visible imager to measure small-scale faint aurora with a spatial resolution of ~1km x 1km at apogee (~4000km altitude), a time resolution of ~10 frames/sec and sufficient sensitivity for auroral intensity of ~1kR. The FUV imager is also required to have high-spatial and high-time resolutions, i.e., a few km x a few km, several frames/sec, to observe small-scale aurora, and sufficient sensitivity for auroral emission at ~1kR. The candidate auroral emission is OI 135.6nm, and/or N2 LBH band (140-180nm). We designed and developed the test model of the FUV imager which consists of a commercial CCD detector which has a FUV sensitivity, objective lenses made of FUV-transparent CaF2 glass, rotational stage and vacuum chamber. We plan to perform sensitivity and radiation tests to the FUV detector in 2021, and demonstrate the performance.

The Martian Moons Exploration (MMX) is a probe which will be launched by the Japanese launch vehicle H-III, and it will navigate the quasi satellite orbit of Phobos and will make a fly-by of Dei-mos.  MIRS (MMX InfraRed Spectrometer) is a push-broom imaging spectrometer in the wave-length range of 0.9 to 3.6 micrometers which is one of the candidate instruments to be installed on the MMX spacecraft.  MIRS will observe absorptions of hydroxide or hydrated minerals on Phobos and Deimos.  It will also monitor the Martian atmosphere with particular attention to spatial and temporal changes as clouds, dust and water vapor.

The international standard for planetary protection has been developed by the Committee on Space Research (COSPAR). The COSPAR Planetary Protection Policy, and its associated requirements, is not legally binding under international law but it is the only internationally agreed planetary protection standard with implementation guidelines for reference in compliance with Article IX of the United Nations Outer Space Treaty of 1967. States Parties to the Outer Space Treaty are responsible for national space activities under Article VI, including the activities of governmental and non-governmental entities. The COSPAR Panel on Planetary Protection (PPP) maintains and updates the COSPAR Policy, and its associated requirements, regularly in various ways. The structure and composition of the Panel, as well as all documents related to the Panel’s activities, can be found at: https://cosparhq.cnes.fr/scientificstructure/ppp. The main goal of COSPAR’s PPP is to prevent any of the space missions to possible habitats from either taking biological material from the Earth and contaminating the target planet/satellite, as well as preventing any contamination from extraterrestrial material returned to Earth if the mission is designed to acquire samples for laboratory analysis [1,2,3]. The five Categories of Planetary Protection outline the recommended measures that an agency should apply to each mission. The Panel reviews all available scientific knowledge before proposing updates to the Policy [4]. Planetary protection guidelines are there to enable safe scientific space exploration for long periods of time and to ensure the protection of our planet Earth [5]. References: [1] Coustenis, A., Kminek, G., Hedman, N. ROOM Journal, June 2019, 44-48. [2] Coustenis, A., et al. (2019). Space Res. Today 205. [3] Fisk, L., et al. (2020) and [4] COSPAR Policy on Planetary Protection. Space Res. Today 208, August 2020. [5] The COSPAR PPP (2020). Research Outreach 118.

Global ionospheric map (GIM) of total electron content (TEC) published by center for orbit determination in Europe (CODE) and vertical ion drifts probed by satellites of ROCSAT-1, DEMETER, FORMOSAT-5, and FORMOSAT-7/COSMIC-2 are used to find the electric field during ionospheric storm and pre-earthquake periods.  Equatorial ionization anomaly (EIA) crest latitudes in GIM TEC are used to estimate the equatorial dynamo electric fields, while ion drifts are employed to directly derive the dynamo electric fields.  Results show that the dynamo electric fields derived by EIA crest latitudes well agree with those by satellite ion drifts.  Thus, the electric fields associated with major storms and before large earthquakes are investigated by GIM TEC as well as ion drifts of ROCSAT-1, DEMETER, FORMOSAT-5, and FORMOSAT-7/COSMIC-2 during 2000-2020.

The mission of Advanced Ionospheric Probe (AIP) onboard FORMOSAT-5 (F5) satellite is to detect seismo-ionospheric precursors (SIPs) and observe ionospheric weathers.  F5/AIP plasma quantities in nighttime of 22:30 LT (local time) and the total electron content (TEC) of the global ionosphere map (GIM) are used to study SIPs of an M7.3 earthquake in the Iran-Iraq Border area on 12 November as well as two positive storms on 7 and 21-22 November 2017.  The TEC and the F5/AIP ion density/temperature anomalously increase over the epicenter area on 3-4 November (day 9-8 before the earthquake) and on the two storm days.  The anomalous TEC increases appearing day 9-8 before the earthquake agrees with the temporal SIP characteristic that the TEC significant increases appear day 14-6 before 53 M≥5.5 earthquakes in the Iran-Iraq area.  This agreement indicates that the temporal SIP of the earthquake has been detected.  The TEC increases frequently appearing specifically over the epicenter area day 9-8 before the earthquake confirms the SIP being observed, while those frequently occurring at worldwide high-latitudes are signatures of the two positive storms.  TEC increase anomalies most frequently appearing in the Iran-Iraq Border area on 21-22 November (day 10-9 before) is coincidently followed by an M6.1 earthquake on 1 December 2017, which again meets the temporal SIP characteristic.  The F5/AIP ion velocity uncovers that the SIPs of the two earthquakes are caused by eastward seismo-generated electric fields, and the two positive storms are due to the prompt penetration electric fields.

Doppler frequency shifts sounded HF (high frequency) CW (continuous wave) Doppler sounding systems with a 5.26 MHz sounding frequency have been using to monitor the traveling ionospheric disturbance (TID) induced by typhoons and earthquakes in Taiwan.  This allows us to have a better understanding on the lithosphere-atmosphere-ionosphere coupling.  Here, TIDs induced by the strong typhoon Meranti in 2016 and the M9.0 Tohoku Earthquake in 2011 are reported.  Results show that prominent TIDs with the period of 10-12 minutes and their associated disturbance origin can be well identified before the typhoon reaches the Taiwan Island.  However, the Doppler frequency shifts become highly fluctuated after the typhoon touches the island.  On the other hand, fluctuations of Doppler frequency shifts agree well with those of co-located seismograms with traveling speeds of 2.5-3.5 km/s, which indicates that the underneath Rayleigh waves of the M9.0 Tohoku Earthquake can effetely activate traveling atmospheric disturbances and TIDs.  Finally, some Doppler frequency shifts coincidently appearing before earthquakes in Taiwan are also presented.

Long-term radio occultation (RO) observations sounded by of FORMOSAT-3/COSMIC and FORMOSAT-7/COSMIC-2 provide an excellent opportunity to investigate plasma structures and dynamics of the ionospheric F2-layer during the sunrise period.  Results show that 1-2.5 hours before the local sunrise, the ionospheric F2-layer height, hmF2, ascends 20-30 km especially at mid-latitudes in winter during the high solar activity period.  The F2-layer starts ascending 30 minutes earlier than the usual in equinox, and becomes unclear in local summer.  Meanwhile, the F2-layer ascending (uplifting) features are not obvious when magnetic declination is negative or the earth’s magnetic field deflects westward.  The F2-layer uplift followed by a sudden descend is attribute to the downward movement of the ionization peak during sunrise.  Moreover, intense observations during the early phase of FORMOSAT-7/COSMIC-2 are employed to find the horizontal structure of ionospheric plasma during the sunrise period.  On the other hand, the electron density RO profiles sounded by FORMOSAT-3/COSMIC and FORMOSAT-7/COSMIC-2 before large earthquakes are presented, and associated possible causal mechanisms are discussed.